`ReflectionFunction::getNamespaceName()` is broken for closures with PHP8.4

[takaram]

Description

The following code:

<?php

namespace Foo;

class Bar
{
    public static function testClass(): \Closure
    {
        return function(){};
    }
}

function testFunc(): \Closure
{
    return function(){};
}

var_dump((new \ReflectionFunction(Bar::testClass()))->getNamespaceName());
var_dump((new \ReflectionFunction(testFunc()))->getNamespaceName());

Resulted in this output:

string(12) "{closure:Foo"
string(12) "{closure:Foo"

But I expected this output instead:

string(3) "Foo"
string(3) "Foo"

https://3v4l.org/QjjJK/rfc

PHP Version

PHP 8.4.0RC1

Operating System

No response

[iluuu1994]

The output is definitely bad, but closures don't have a namespace. Not sure what the correct output would be. Related to #12907.

[iluuu1994]

Oh, I see this only changed in 8.4.

[iluuu1994]

The name was previously Foo\{closure}, and is now {closure:Foo\Bar::testClass():9}. It seems this is related to #13550. Hence, the logic in ReflectionFunctionAbstract::getNamespaceName() is now broken, as it's looking for the first \ and, if present, returning everything up to it. /cc @TimWolla

php-src/ext/reflection/php_reflection.c

Lines 3605 to 3610 in 1da352c

	zend_string *name = fptr->common.function_name;
	const char *backslash = zend_memrchr(ZSTR_VAL(name), '\\', ZSTR_LEN(name));
	if (backslash) {
	RETURN_STRINGL(ZSTR_VAL(name), backslash - ZSTR_VAL(name));
	}
	RETURN_EMPTY_STRING();

[TimWolla]

Related to #14001 (which fixed it for getShortName()) and #14087 which follow-up fixed that for FCC. I'll send a PR tomorrow.

[TimWolla]

This also affects inNamespace(). My PR will fix both.